soma_big.cc

#include <iostream>
#include <sstream>
#include <vector>
#include <deque>
using namespace std;

bool is_digit(const char c) {
  return (c >= '0' && c <='9');
}

struct BI {
  vector<int> number;

  void load_vi(deque<char> & vi) {
    stringstream ss;
    for (char c : vi) {
      ss << c;
    }
    int n;
    ss >> n;
    number.push_back(n);
    vi.clear();
  }

  friend istream & operator>>(istream& in, BI & bi) {
    deque<char> n;
    char c;
    while (is_digit(in.peek()) && in.get(c)) {
      n.push_front(c);
    }
    deque<char> vi;
    for(char ci : n) {
      vi.push_front(ci);
      if(vi.size() > 7) {
        bi.load_vi(vi);
      }
    }
    if(vi.size() > 0) {
      bi.load_vi(vi);
    }
    return in;
  }

  friend ostream& operator<<(ostream & o, const BI & bi) {
    for (auto it = bi.number.rbegin(); 
        it != bi.number.rend(); 
        ++it) {
      o << '\'';
      o << *it;
    }
    return o;
  }

  void add(const BI & o) {
    if(number.size() < o.number.size())
      number.resize(o.number.size());

    for(int i = 0; i < o.number.size(); ++i)
      number[i] += o.number[i];

    number.resize(number.size() + 1);
    int d = 0;
    for(int i = 0; i < o.number.size(); ++i) {
      int nd = (number[i] + d) / 100000000;
      int nr = (number[i] + d) % 100000000;
      number[i] = nr;
      d = nd;
    }

  }

  friend BI operator+(const BI & a, const BI & b) {
    BI r;
    r.add(a);
    r.add(b);
    return r;
  }

};

int main() {
  BI a;
  BI b;
  cin >> a;
  cin >> std::ws;
  cout << "read a\n";
  cin >> b;
  cout << "read b\n";
  cout << (a + b) << '\n';
  return 0;
}